CVE-2026-93394 (CVSS 3.7)

Description

A flaw in libmongoc's SCRAM authentication implementation caused the client to continue the authentication handshake and transmit the client proof even when a nonce mismatch was detected in the server's first message. An unauthorized party with a man-in-the-middle position could exploit this by injecting a crafted server-first-message containing a controlled salt and low iteration count, then capturing the resulting client proof to perform offline password cracking. This vulnerability is mitigated by TLS, which is standard in production deployments.

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CVSS v3.1 Score

3.7

LOW

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS — Exploit Prediction

0.0032

Probability of exploitation

0.24%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-303 CWE-303

References

Other References

https://jira.mongodb.org/browse/CDRIVER-6315

Frequently Asked Questions

What is CVE-2026-93394? +

A flaw in libmongoc's SCRAM authentication implementation caused the client to continue the authentication handshake and transmit the client proof even when a nonce mismatch was detected in the server's first message. An unauthorized party with a man-in-the-middle position could exploit this by injecting a crafted server-first-message containing a controlled salt and low iteration count, then capturing the resulting client proof to perform offline password cracking. This vulnerability is mitigated by TLS, which is standard in production deployments. It has a CVSS v3.1 base score of 3.7 (LOW).

How severe is CVE-2026-93394? +

CVE-2026-93394 has a CVSS v3.1 score of 3.7 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0032, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-93394? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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